Reserved words — SendLang docs

Both lists below are ReservedWords() from the parsers, dumped at build time.

The rule

A reserved word may not be used as a bare name. There are exactly three bare name positions in the languages:

an event name — count(open ...)
a property name inside a where — where url contains "..."
an aggregate field name — sum(amount of ...)

That is all. Everywhere else, names are either qualified (attr.x, activity.x) or quoted ("onboarding"), and neither can be confused with a keyword — so neither is restricted.

This is why all of the following are perfectly legal:

SendQL

attr.count = 5 and in list "segment"

SendFlow

workflow "Reserved words are fine when quoted" v1 {
  enter on segment "trial-started"

  // A topic called "timeout" is a string, so it cannot collide with anything.
  send "welcome" via topic "timeout"
}

And why this is not:

SendQLRejected

exists(within within 7d)

"within" is a reserved word and cannot be used as an event name

The parser cannot tell whether that first within is an event called within or the start of a window. So it is rejected, and the error says exactly why.

SendQL

all
and
avg
between
contains
count
ends
exists
false
first
from
has
in
is
known
last
list
max
min
not
now
of
opted
or
out
segment
starts
subscribed
sum
suppressed
to
true
unknown
unsubscribed
where
with
within

SendFlow

SendFlow reserves everything SendQL does, plus its own workflow keywords.

Inherited from SendQL

add
after
all
and
avg
before
between
cap
contact
contains
count
else
ends
enroll
enter
event
every
existing
exists
exit
false
first
forward
frequency
from
has
hold
if
in
is
known
last
list
max
min
not
now
occurrence
of
off
on
once
opted
or
out
per
reentry
rematch
repeat
segment
send
set
since
split
starts
subscribed
sum
suppressed
timeout
timezone
to
topic
transactional
true
unknown
unsubscribed
until
up
via
wait
when
where
window
with
within
workflow

Two words that are not reserved

attr and activity are not reserved words. They are qualifiers, and they are only meaningful directly before a ..

Which is exactly why attr.count works: count is reserved, but the name being parsed there is not a bare count — it is the property half of a qualified reference, and the qualifier has already told the parser what to expect.